High Intensity Interval Training (HIIT) has gained much popularity recently and was even recognised as the number one fitness trend of 2017. On the other end of the spectrum, Low Intensity Steady/ Sustainable Training (LISS) has consistently been the classical choice of exercise for many when it comes to cardiovascular work. Many have trouble deciding on which to incorporate as part of their exercise regimen and usually end up deciding based on the amount of time they can spare to exercise. To make a more wise and purposeful decision, let us take a closer look at the goals and effects of the two distinct training modalities.

High Intensity Interval Training (HIIT)

What it is:

As its name suggests, HIIT involves doing multiple repetitions of medium to high-intensity exercises with short breaks in between.

Pros and Cons:

The main benefit of HIIT over LISS is its ability to train both your aerobic and anaerobic capacity, within a short span of exercise time. However, the high physical stress of HIIT makes it a less ideal training style when your body is already tired—e.g. due to other high intensity workouts over the week or stress from work.

What to take note of:

While HIIT encourages you to push yourself, it is important to keep in mind your physiological limitations. Stick to a work: rest ratio between 1:1 and 1:2 (scale accordingly to your level of fitness) to prevent overexertion of your muscles and to allow your body time to recover sufficiently.

Low Intensity Steady/ sustained training (LISS)

What it is:

LISS is the opposite of HIIT; it utilises a longer duration of work(usually above 30 min), is of much lower intensity and involves few to no breaks. A common classic example of LISS includes light jogging, swimming or brisk walking.

Pros and cons:

Over the long-term, LISS improves your overall fitness, increases your aerobic capacity and aids in recovery after intense workouts. It is not as physically tiring as HIIT and thus involves a lower risk of overexertion. However, LISS typically mandates more exercise time due to its intrinsic nature, making it unfavourable for those with tight work schedules. Furthermore, unlike HIIT, it largely focuses on one's aerobic capacity (i.e. little to no strength or power development).

What to take note of:

While LISS seems much less effective than HIIT, you should bear in mind that it is not advised to entirely replace LISS with HIIT sessions. Instead, LISS can be used together with HIIT for holistic improvements in health and fitness.

Neither type of training is arbitrarily better than the other. Rather, both serve different purposes and have different outcomes. Your exercise regimen should not be crafted randomly or purely based on the amount of spare time you have. Be specific about your goals and pick the type of training best suited to helping you achieve them. When it comes to cardiovascular training, you'll find that there's always a place for them!